西南地区植被变化与气温及降水关系的初步分析

Preliminary Analysis on the Relationships between NDVI Change and Its Temperature and Precipitation in Southwest China

利用卫星遥感植被归一化指数（NDVI）资料和西南地区96个实测台站的月平均气温以及降水资料，初步分析了西南地区植被变化与气温及降水的关系。结果表明：近20年来西南地区植被覆盖状况较好，其中夏季植被覆盖最好，冬季植被分布空间差异最大；西南地区植被整体呈增加趋势，同时也存在较明显的季节和区域差异：春季西南大部分地区植被以增加为主，夏季、秋季全区以减少为主，冬季则以增加为主且存在明显的东西反向特征，东部减少西部增加。时滞互相关分析表明：西南地区11～2月份的植被对超前其1～2个月的气温以及夏季的植被对春季气温的敏感性比较大，3～4月的植被生长对上年夏季的降水敏感性比较大；同期时，1～3月植被和气温为正相关关系，6～9月的植被生长和降水为明显的负相关关系；在植被超前气候的条件下，1～2月的植被和滞后1～2个月的气温呈正相关关系，与滞后1个月的降水有明显的负相关关系。

Based on the monthly Normalized Difference Vegetation Index （NDVI） data that it is made by GIMMS （ Global Inventory Modeling and Mapping Studies ） workgroup of National Aeronautics and Space Administration （ NASA ） and the monthly mean air temperature, precipitation data from 96 stations in the Southwest China for the period of 1982 to 2001, the change characteristic of NDVI and the relationship between the NDVI and the air temperature, precipitation have been studied. The results are summarized as follows： In the last 20 years the vegetation cover is well over Southwest China. The NDVI in spring is best and the biggest regional differences is in winter. NDVI is mainly increased over all Southwest China. Meanwhile, There are significant regional and seasonal differences in there. NDVI is increased slightly in spring. It is mainly increased over all Region , especially sharp in south. In summer and autumn NDVI is basically decreased in Southwest China , Winter NDVI is mainly increased over all Southwest China. There are significant regional differences with the main feature opposite the change direction between the east and the west. It is reduced in east and increased in west mainly. The time lag partial correlation between NDVI and temperature, precipitation show that the NDVI in November - February have a big sensitivity for tem- perature in September- January, the same complexion is NDVI in summer and temperature in spring, the precipitation in last summer plays an important role to the NDVI in March - April. In the meantime, NDVI has the best positive correlation with temperature in January to March and the best negative correlation with precipitation in June to September. When climate condition lag behind the NDVI, the NDVI in January to February not only has the best positive correlation with the temperature lags NDVI 1 to 2 months but also has the best negative correlation with precipitation lags NDVI 1 month.